The present invention relates generally to pharmaceutical compositions and methods of use thereof which involve using IL-12 as a therapeutic agent or an adjuvant, particularly in vaccines against cancer; and more particularly, relates to methods and compositions for enhancing IL-12 activity.
Interleukin 12 (IL-12) is an immunoregulatory cytokine with potent antitumor, antiparasitic, antiviral and antimicrobial effects [M. J. Brunda, Res. Imm., 146:622 (1995); G. Trinchieri, Annu. Rev. Immunol., 13:251 (1995)]. Many of its activities are attributable to its ability to induce Th1 CD4+T cell differentiation, CD8+T cell cytotoxicity and natural killer (NK) cell activation. IL-12 is critical to the development of cell-mediated immunity (CMI), being a potent inducer of gamma interferon (IFNxcex3) from T and NK cells. IL-12 is also proinflammatory through its ability to induce production of IFNxcex3, tumor necrosis factor alpha (TNFxcex1), granulocyte-macrophage colony stimulating factor (GM-CSF) and other cytokines by T and NK cells. IL-12 is required for the development of Th1 responses, is necessary for delayed type hypersensitivity (DTH) responses, and is an enhancer of NK cell cytotoxicity [G. Trinchieri, Blood, 84: 4008 (1994); G. Muller et al., J. Immunol., 155: 4661 (1995)]. Monocytes are the principal producers of IL-12 in peripheral blood mononuclear cells (PBMC), and monocyte/macrophages are thought to be the principal producing cells in vivo [Trinchieri, cited above; A. D""Andrea et al., J. Exp. Med., 176: 1387 (1992); R. T. Gazzinelli et al, Proc. Natl. Acad. Sci. U.S.A, 90: 6115 (1993)].
IFNxcex3 is a particularly important mediator of IL-12 effects. Among other actions, IFNxcex3 activates macrophages and induces the production of nitric oxide. IFNxcex3 also acts on many other types of cells, including tumor cells, and its ability to upregulate MHC expression, slow cell proliferation, and inhibit angiogenesis may contribute to IL-12""s antitumor effects [Voest, E. E. et al, J. Natl. Cancer Inst., 87:5813 (1995); Sgadari, C. et al, Blood, 87:3877 (1996); and Coughlin, C. M. et al, J. Clin. Invest., 101:1441 (1998)].
Therapeutic effects of IL-12 administered systemically have been reported [e.g., F. P. Heinzel et al, J. Exp. Med., 177:1505 (1993) among others]. EI-12 has also been found to be an effective adjuvant for a variety of vaccine antigens [U.S. Pat. No. 5,723,127]. However, despite its desirable therapeutic effects, the therapeutic use of recombinant IL-12 (rIL-12) can be accompanied by severe toxicities. Dose and schedule dependent toxicities have been seen during clinical trials [Atkins, M. B. et al., Clin. Can. Res., 3:409 (1997); Cohen, J., Science, 270:908 (1995)] and in mice [Coughlin, C. M. et al, Cancer. Res., 57:2460 (1997)]. Administration of rmIL-12 during LCMV infection in mice has been associated with adverse immunological effects manifested by higher viral loads, decreased anti-viral CTL activity, and poorer outcome. TNFxcex1 is implicated in rmIL-12 suppressive effects during LCMV infection [Orange, J. S. et al, J. Immunol., 152:1253 (1994)].
Further, while studying the effects of rmIL-12 in A/J mice during vaccination of genetically modified irradiated, SCK tumor cells, the present inventors observed that IL-12 transiently suppressed cellular immune responses in mice. High doses of the cytokine transiently suppressed tumor protection in vivo and proliferative responses of splenocytes to T cell mitogens in vitro [Kurzawa, H. et al, Cancer Res., 58:491 (1998)]. These effects of high-dose rmIL-12 were generalized, affecting responses to allogeneic vaccination and splenocyte mitogenic responses in naive mice of many strains, and appeared to result from impairment of immune effector function rather than failure to induce immunity.
Therapeutic applications of IL-12 may benefit from reduction or elimination of its transient immunosuppressive side effects. Approaches to reducing or eliminating IL-12 immunosuppression include using fewer doses of the cytokine. While this approach may be beneficial [Noguchi, Y. E. et al, Proc. Natl. Acad. Sci., USA, 92:2219 (1995)], finding the xe2x80x9cproperxe2x80x9d regime of IL-12 administration is likely to be quite involved and the results idiosyncratic. Inhibiting IFNxcex3 action is another alternative for avoiding IL-12 immunosuppression, but is an impractical approach which is severely compromised by the fact that IFNxcex3 may be the primary mediator of IL-12 therapeutic effects.
Thus, there remains a need in the art for methods and compositions which can eliminate the immunosuppressive effect of IL-12, particularly in situations where an enhanced and rapid adjuvant effect is desirable, and in situations where lower doses of IL-12 are desired for therapy.
In one aspect, the invention provides a method for enhancing the adjuvant effect of IL-12 comprising co-administering with IL-12 and a vaccine antigen, an effective amount of an agent that inhibits or reduces the generation of, or that breaks down, absorbs, metabolizes or eliminates, nitric oxide in vivo (hereafter referred to as xe2x80x9cnitric oxide inhibiting and/or neutralizing agentxe2x80x9d). The vaccine antigen may be a mammalian tumor cell antigen or an antigen from a pathogenic microorganism.
In another aspect, the invention provides a method for reducing the immunosuppressive effects of IL-12 treatment comprising co-administering with IL-12, an effective amount of the nitric oxide inhibiting and/or neutralizing agent described above.
In another aspect, the invention provides a method for reducing the toxicity of IL-12 treatment comprising co-administering with an effective dose of IL-12, an effective amount of a nitric oxide inhibiting and/or neutralizing agent. The effective dose of IL-12 may be a low dose thereof.
Still another aspect of the invention is a therapeutic composition comprising IL-12, characterized by reduced toxicity in mammals, which comprises IL-12, preferably a low dose thereof, and an effective amount of a nitric oxide inhibiting and/or neutralizing agent in a pharmaceutically acceptable carrier.
In yet a further aspect, the invention provides an adjuvant composition suitable for use with a vaccine antigen comprising an effective adjuvanting amount of IL-12 and an effective amount of a nitric oxide inhibiting and/or neutralizing agent in a pharmaceutically acceptable carrier.
In still a further aspect, the invention provides a vaccine composition comprising an effective adjuvanting amount of IL-12, an effective amount of a nitric oxide inhibiting and/or neutralizing agent and an effective protective amount of a vaccine antigen in a pharmaceutically acceptable carrier.
Other aspects and advantages of the present invention are described further in the following detailed description of the preferred embodiments thereof.